What causes pink discoloration on white concrete?
This is usually caused by a reaction between the alkalies in the concrete and phenol-formaldehydes in the plywood form. The reaction produces a number of pink colored dyes. Often the discoloration will disappear within periods ranging from two weeks to three months, depending on the amount of discoloration and the climate. The discoloration may be removed by scrubbing with sodium hypochlorite. Pinking may be prevented by applying a lime and water slurry to the forms ahead of time and allowing them to stand a day or more. The slurry should be washed off before the form release agent is applied.